In a simple Caesar cipher (such as the one in this challenge), the number of characters you rotate is fixed for the whole ciphertext.

In practice, this means that once you find the correct rotation number, the whole text will be deciphered.

So, if after you found the correct key (I think you assume it is the correct key because most words look like they are in English) some words still look like random characters... Well, maybe they're supposed to be random characters :)